[HTTPS-Everywhere] "Author not verified" while trying to install "HTTPS Everywhere 2.2" (Firefox 14.0.1, Mac OS X 10.6.8)

[Tagglez Tagglez]

Hello,

I am trying to install "HTTPS Everywhere" on a fresh install of Firefox 14.0.1, using Mac OS X 10.6.8.

I went to the website

https://www.eff.org/https-everywhere

and clicked on the "Install in Firefox - version 2.2 stable" icon on the page.  Firefox responds by showing me a message "Firefox prevented this site (www.eff.org) from asking you install software on your computer" and an "Allow" button.  When I click on the "Allow" button, and the extension has finished downloading, I get a warning dialog box about installing downloads from trusted authors, and the caption "You have asked to install the following items", followed by a list box with the item "HTTPS Everywhere (Author not verified)".

Should I go ahead and allow the installation to complete even with the "Author not verified" message, or should I assume that the extension Firefox downloaded is not authentic?  Having been hit by a malicious Trojan before (when I was tricked into downloading a so-called "Flash plug-in update" for Firefox many years ago, which has kept me away from Firefox until now), I am quite cautious  these days.  Are there alternative ways of confirming the authenticity of the downloaded "Https Everywhere" extension along the lines of an MD5 check-sum or something?

Thanks in advance, and I hope I'm sending my email to the correct forum.